timeidx(varargin)

 function val = timeidx(varargin)
%TIMEIDX returns numeric index given time string.
%   D = TIMEIDX(T) returns index value in relative days which is suitable for
%       DATENUM math. To work in hours multiply by 24, for seconds multiply
%       by 24*3600, etc. T can be a time string (DD:HH:MM:SS) where DD, HH
%       and MM are incrementally optional and SS can include a decimal
%       fraction. For multiple time values T must be a cell array of strings.
%       The result is the same size/shape but type DOUBLE.
%
%   D = TIMEIDX(T1,T2) returns a range of values. T1 and T2 are individual
%       time strings (as above) and the result is a 1x2 DOUBLE array.
%
%   N = TIMEIDX(...,FS) instead returns index values in sample units relative
%       to the beginning of a record where FS is samples/second. Sample
%       values are rounded to integer values. Time 0 corresponds to sample 1.
%
%Example 1: operation times out after 5 minutes
%   t2 = now+timeidx('5:00')*24*3600;
%   while ~done && now<t2
%     %wait for something else to happen
%   end
%   if ~done
%     error('Operation failed to complete in 5 minutes')
%   end
%
%Example 2: specify portion of WAV file to read
%   range = timeidx('2.5','1:02.5',Fs); %1 minute after 2.5 second delay
%   x = wavread('myfile.wav',range);
%
%See also DATENUM, DATESTR

% Copyright 2008-2010 The MathWorks, Inc.

%defensive programming
error(nargchk(1,3,nargin))
error(nargoutchk(0,1,nargout))

[timeString,Fs] = ParseInputs(varargin{:});

%convert time string(s) to datenum value(s)
if iscell(timeString) %array
  val = zeros(size(timeString));
  for k=1:numel(timeString) %each time
    val(k) = StringToDays(timeString{k});
  end
else %scalar
  val = StringToDays(timeString);
end

%optionally convert datenums to sample indices
if ~isempty(Fs) %Fs specified
  val = round(val*(24*60*60)*Fs)+1;
end

%----------------------------------------------------------------------
function timeVal = StringToDays(timeString)
multipliers = [1 60 60^2 24*60^2]./(24*60^2); %SS MM HH DD
parts = fliplr(regexp(timeString,':','split')); %SS MM HH DD
if numel(parts)>numel(multipliers)
  error('Too many parts')
end
timeVal = 0;
for k=1:numel(parts)
  timeVal = timeVal + str2double(parts{k})*multipliers(k);
end

%----------------------------------------------------------------------
function [t,Fs] = ParseInputs(varargin)

t = varargin{1}; %arg1 must be T1

if nargin>1 %arg2 could be T2 or FS
  if isa(varargin{2},'double')
    Fs = varargin{2};
  elseif isa(varargin{2},'char')
    t = varargin(1:2);
  else %logic flaw
    error(['Expected DOUBLE or CHAR not ',upper(class(varargin{2}))])
  end
end

if nargin>2 %arg3 must be FS
  if isa(varargin{3},'double')
    Fs = varargin{3};
  else %logic flaw
    error(['Expected DOUBLE not ',upper(class(varargin{2}))])
  end
end

if ~exist('Fs','var')
  Fs = '';
end